Frequency indicating and counting arrangement



May 30, 1950 A. E. BACHMANN FREQUENCY INDICATING AND COUNTING ARRANGEMENT 3 Sheets-Sheet 1 Filed Sept. 50, 1947 INVENTOR N a M? m m E;/% n T/u A m 6 mm y 1950 A. E. BACHMANN 2,509,952

FREQUENCY INDICATING AND COUNTING ARRANGEMENT Filed Sept. 30, 1947 3 Sheets-Sheet 2 FIG. 2.

. 1| 6 ,69,70 'l I 40 (2 -LF x hwjw l I 25 I {3/ f 2,2 I

a g 32a g 5 k 5-1 a 55,56 INTERMITTENT 4 46 INTERMITTENT GEAR 1 44 GEAR(5:/J 33 C COARSE FREQ. CHANNEL SELECTION CKT, WRADIO aNE-aimfiasoizms TRANS a FREQ CHANNEL 0 SELECTION CKT. r'"-" b /6 some 0F MASTER FREQUENCY 3 43 INVENTOR.

ALBERT E. BACHMANN ATTORNEY.

May 30, 1950 A. E. BACHMANN FREQUENCY INDICATING AND COUNTING ARRANGEMENT Filed Sept. 30, 1947 3 Sheets-Sheet 3 INVENTOR.

ALBERT E. BACHMANN ATTORN EY.

Patented May 30, 195

FREQUENCY INDICATING. ANDJCOUNTING ARRANGEMENT AlbertE"; Baehmalm', Cedar Rapids; Iowa, assign or to Collins Radio-Company; Cedar Rapids, Iowa, a. corp.oration'of Iowa.

Application September .30, 1947;1Serial No.. 777,045

17 Claims. v (01. 116e-124) Thisinvention relates to frequency selection systems and more especially-to a frequency coun terandindicatorfor use in suclrsystenis:

A-principal object of th'einvention-is to provide an improved meehanicalcounting device which has a. plurality of indicator dials or drums oneof'" which indicatessuccessive relatively widely different numbers of turns of a control sh'aft orthe'-like; andanother dial'or drum which indicates uni-form increments between said successive widely different numbers of turns.

Another principal object is to' provide a mechanicalcounting device having a series-=of indicator dials which are successively and" cumu-'- latively-operated by one-control to indicatesue cessive and relatively coarse settings of a shaft or the like, andanother dialato indicateuniform incremental settings between saidcoarsesettings: The said-series of coarsedialscan beset independently and cumulatively by their respective control knobs. However the incremental dial can be independently set to indicate aseriesof subdivisions betweenthe coarsesettings of saidseries of dials: The arrangement is such thatyif" desired; continuous rotation of the incremental Y dialcan also causethe cumulativesetting of thesaid series ofdials.

Another object is to providea novel -mechanical counting dial for an arrangementwhich isrequired to beadjusted'to' any one of aseries ofcoarse settings, and=which is also requiredtobe adjusted to any integral subdivision between suecessive coarse settings.

Another object is to provide-an improved fre quency counting device-for wave frequency-gem erator or selector systems, wherein the system can beadjusted to any oneof a series of "frequencies relatively widely spacedin the frequencyspec trum, and also to any desired-incremental fre-- quency.

A- feature of the inventionrelates-"tea wave-'- frequency generator or selector system having-a coarse frequenc selector channel, andan incre= mental or fine: frequency selector channel, thesettings of both channels determining-'a'single desired output frequency; which settings are con-'- trolled bythe number of turns-of "respective control shafts, in conjunction with a special counting dial having a plurality of dial sections an ranged to be set respectively in accordance with said control shafts.- The dial section for the incremental frequency is arranged' to'be adjustedindependently of the other dial section; and said" otherdial section 1 is constituted of 2, series of successively' cumul'ative digit dials all of which can-be adjusted independently of the incremental dial. However the lowest dig-it dial of said other dial sectioncanalso be controlled cumulatively by apredetermined number of complete turns of said incremental dial.

Another-feature relates to a numerical counting-dial arrangement having two dial sections, one'sectlon con-sistingof a single rotatable'dial, and the other-section consisting of aseries of cumulativerotatable dials.- Control means are provided-"for separately operating the two dial sections, but one-of the dials of said'other'section is arrangedtobe operated cumulatively by the firstdia'l section;

Another feature relates to a direct readingfrequency counting mechanism for wave frequency generators- 01" selectorsof the type which can" be setin' successivecoarse steps to produceany one of aseries-offrequencies'relatively widely' spaced in the-frequency spectrum, and can also beset" in incremental'steps'to produce'any de, sired incremental frequency within the range of each coarse setting.

Another feature relates to an improved. direct. reading frequencycountin'g and indicating dial for use with wave frequency generating or'selecting systemsof'the kind disclosed-for example in application Serial-No. 656,666, filedFebruary 27, 1946', and issued as U. S. Letters Patent No. 2445,6641

A' still further feature relates to the novel organization; arrangement, and relative inter;-

connection' of parts'whi'ch cooperate to provide; an

improved" direct reading dial for" a multi-frequ'ency' selection system;

Otherfeatures and advantages not particularly set forth' willbe'apparent after a consideration of the" following detailed descriptions and'the.

appende'dclaims.

In the drawing which represents one preferred embodiment;

Fig: 1 is' a frontview of the frequency counter and indicator device according to the. invention. Fig. 2 is a compositesmechanicaily schematic an'd'electrica'lly'schematic diagram of a frequency selectingand indicating system according to the spaced in the frequency spectrum, by first selecting a frequency range within which the desired frequency is situated, and then incrementally obtaining the desired frequency. A typical system of this kind is disclosed in said application Serial No. 650,666, and is represented schematically in Fig. 2 by the master frequency source II! and by the associated coarse frequency channel selection circuit I I, the fine or incremental frequency channel selection circuit i2, and a suitable load circuit such as the radio transmitter I3 with its associated antenna I I. As described in said U. S. Letters Patent, the source I can be any well-known device for generating simultaneously a very large number of frequencies, for example it may take the form of an electron tube oscillator which is connected through a harmonic generator to produce the harmonic frequencies, or it may take the form of a multivibrator for producing these frequencies. In certain kinds of radio transmission it is necessary to switch the radio transmitter I3 rapidly to any one of a very large number of radio frequencies, and merely for explanation it will be assumed that these frequencies lie between one megacycle and ten megacycles with successive final frequency spacings of 250 cycles per second. As also described in said U. S. Letters Patent, the coarse frequency selecting channel II is arranged to be set in a step-bystep manner by means of a hand-wheel or knob I5, and the fine or incremental channel I2 is arranged to be set by the respective hand-wheel or knob It. It will be assumed that the knob I5 is arranged to be turned during each revolution through four equal steps approximately 90 apart, and that each step corresponds to a twenty-five kilocycle range of the selector Il. Also for purposes of explanation, it will be assumed that the knob I6 is likewise arranged to be operated during each revolution through four successive steps each representing an incremental frequency of 250 cycles per second from the selector I2. The knobs I5 and I6 are also mechanically coupled through respective mechanisms to be described, to the frequency indicating and counting dial I 1. This dial is constituted of three sections I'Ia, Ill; and He. The section Ila consists of a single wheel or drum carrying four frequency markings equally distributed around the periphery, namely 000 and 250, 500 and 750. The dial section I'Ia is thus arranged to be operated through suitable gearing and shafting in unison with the knob I6. Thus for each of the four successive positions of knob IS, the dial section Ila will indicate one of the four above-mentioned incremental frequencies in cycles per second. The dial section I ll) consists of a dial wheel I 8 with ten equally spaced numerals and is arranged to be operated in a 1:10 ratio with respect to section I'Ia under control of knob I6.

On the other hand, the dial section We consists of three separate dial wheels I9, 20, 2I. Each of these wheels I9 to 2I carries ten equally spaced digits 0 to 9 around its periphery in the manner well-known in dial counters. The dials I9 to 2! are arranged to be cumulatively operated in sequence. The dial I8 is also arranged to be set in a 10:1 ratio with respect to dial I9 under control of an intermittent gearing which is controllable by knob I5. Thus, when the dial I8 makes one complete turn either as a result of turning knob I5, or as a result of turning knob I6, it advances the dial I9 through one-tenth of a turn. Likewise, when the dial I9 makes one complete turn, it advances the dial through one-tenth of a turn, and a similar arrangement exists between the dials 20 and 2|. Since cumulative mechanisms of this general type are wellknown in the dial counting art, description thereof is not necessary herein. Thus dial I8 is arranged so that it can be set either by the knob I5 or by the knob I0. However, the knob I 5 is so connected, that for each quarter-turn thereof between its respective positions a, b, c and d, it advances dials I8, I9, by twenty-five kilocycle steps. In other words, the output of the selector I I is varied one hundred kilocycles for each complete revolution of knob I5. In the particular setting illustrated in Fig. 2, the selector I I is producing an output frequency of 2313 kilocycles. If the knob I5 is turned so as to bring the indi cator pointer e into the 0 position, the selector II will produce a frequency of 2338 kilocycles which will be indicated on the dial section I'Ib. Likewise, if the knob I5 is turned so that the indicator pointer e is in position b, the selector II will produce 2363 kilocycles which will likewise be indicated on dial section I'Ib. On the other hand, the knob It for each complete rotation causes the output of the frequency selector channel I2 ot vary over a range of 1000 cycles per second, or 250 cycles per second for each quarter-revolution of knob I6. Consequently, for twenty-five complete revolutions of knob It, one hundred uniform incremental frequencies can be selected for each twenty-five kilocycle setting of selector I I.

The mechanical controls between the knobs I5 and I6 and the counting dial H, are schematically indicated in Fig. 2. Thus the knob I6 is connected through suitable shafting 22, 23 and suitable gearing to operate the dial I'Ia in unison therewith, at the same time giving rise to increments in the output frequency of selector I2 of 250 cycles per second. The knob I6 is also coupled by shafting 22, 23 and an intermittent gear arrangement 2c having a ratio of five to one. That is, for each complete turn of knob I6, the shaft 25 is advanced one step. The shaft 25 is coupled to the ring gear 29a of a differential gear unit 29 through suitable step-down gear 2'Ia having a step-down ratio of two to one. Shaft 28 which is attached to gear 29a, drives the dial I8 through one to one ratio gears 53, 5t. Thus, there is a ten to one step-down intermittent ratio between knob I6 and dial I8, so that for every complete turn of knob IS the dial I3 is advanced one-tenth of a turn. The intermittently rotatable shaft 25 is also coupled to another shaft .iI through an intermittent spur gear combination 32a, 32b, with a step-down ratio of five to one. Shaft 3I is coupled to the ring gear 36a of another differential gear unit through step-down gears 34a, 341) with a step-down ratio of twelve to five. The sun gear 361) of this diiferential is then coupled to shaft 35 through gears 64, having a one to one gear ratio. Shaft 35 is then coupled to shaft 31 through an intermittent spur gear arrangement 38a, 38b having a step-down ratio of ten to six. Shaft 3? drives the dial I 9 which for every complete turn drives the dial 20 one-tenth of a turn. By following through the above-described shaft and gear arrangement, it will be seen that the step-down ratio between knob I 6 and dial I9 is one hundred-to-one. Thus, by rotating knob I6, the dials Ila, I8 and I9, continuously indicate the frequency to which the transmitter I3 is being set. The mechanism for controlling the channel I I and the dials I8, I9, in their twenty-five kilocycle steps independently of knob l 5; comprises: thefknoh; I &;which: is 0031:: turn "meshes" with: the; gear; 221: attached:.to v. the; pled through shaits;.39, gears-55; 55;.511 ,",58-'. :59etodial. sectiongllansotthat :thiszdiallsection.rotates shaft 40, and thence-ithroughigeairsefi;:69;Ill-the in unisoniwiththeknob, l6, Shaft13|.drivesathe differential gear: arrangement; 2 8::butrwitlrastepspur gears;.:34a;. 31412:,- .havingaistepedown:ratio :of down ratio oitwoto one,and,;thence to theishaita 5- twelve to five. Gear; 34b is; ingwmesh 'withrthe 28.- which, drivesF dial! I8; The; knobs l5: iS:f also. ing ar-136mm.thedifiierentialfifi: Likewise the coupled. through shaft, 39, ,thence through gears: spurgear 2 1a on-shaft 25 aisin mesh iwith thering; 59, 62, 63 to shaft 4| with a sten-idown'ratidof six; ear. 29a:. he differentiallfla Thei -differential to five. Shaft M is also; coupledtoshait'; 3.5; gear-inconsistent .a;.planetary:gear systemucom through gears-64, 651andthe difierontialgeanar: prising. planetary. gears 472911,. 2.90, (see-iv Fig; 4), rangement 36 but with a, step -tup ratimofroneid whichrare:afiixed;togtheicommonshaft nd pass two. Shaft 35 as abovedescribed is ,coupled to dial ing through the ring gear. 2.9a. The planetary I9 through .the step-down intermittenttgearsiiis ea s 91x2 ar nrmeshiwith h ir r sp ctivea 38bhaving a.ratio of temtovsixh By followingthe: u ars;29e;12o9f.. Sun:gear,29eardrivestaigeari above-described shaftingandgearing oonnections; r in 53', .54,- whichzin tumdrivethexdiaLlBa it will .be seen that dialsgl 82nd I9;continuouslyain--= The control 'oknob, I5 rotates; the. bevel..- ears dieate; the twenty'rfiverkilooycle incrementsrpro= 55;. wh n rn riv shaft Ml-i as duced,bmquarterrrotationaof knob rl5'.- Bylmieans. Well as, earsiii; 6B- Gearsv59 riv s-aa ar a n of the differential gear;arrangementszikand 136; it v 53,1 Wh hz turni ive the aw 35b; is possible t o e at th dial ls; [9 ,41]; and, 29; of thedifierentialfifie Theishaftzotsun germ-3%; independently of. the dial "0;. Likewise, it isbposcarries a gear 64arvhiehmesheewitha correspond-a sible to operate the dia1.l1a1soe ashtmobtainoanyt in ear t5wattach dl othe intermittentgear 3311. other desired uniform incremental,- setting; be.-.- Gear 233a drives--the correspondingSpur ar. 19; tween the successivetwentyefivekilocycle settings under control otthe asseeiatedintermittentgloekaof dials 1-3 and 19. The movement oteitherrof 2.5: eiz earsfific, 38 Gear 3fidr.thr lieh: ui a le: the knobs [5 or lsdoes notlaiiectwthepreyious, spur gears Bit-61, drivesitheildialltegby'meaalstot; setting of the other-knob. shaft 68 which: passes thisoughihe;dials:.:;,2'1;

The aboveedescribed; arrangement isparticu Gear B0,:thronghgears-.Bflfiifl; isscoupleduto the larly useful where; the. transmitter; 3f .S.Ieql.1'iILed: 1 sun gea-r .291 (seetFigm 4)., oi'theplanetary or difto be switched: rapidly-towidely, difierentzfraaogferential gear y fl nflllfi' v Th y means offlthe quencies. For example, itthetransmitter I3. is twoiplanetary gfiairvsystemsfinlrandts-p operating at a frequency of; 2',313;250.kilooycles sible toeprovide independent y t fl ede as indicated by thesettingoof; the, equipment in trol of dialsJBaandJB: by 'means; of ieithereof the Fig. 2, andit is required-tobeshiitedrto,2363.250 knobs .l5;or 16: It .will be understood, otcourse; kilocycles, all that is necessary; is toturn theknob. 35; that thendialul 1 ran be'continuously. operated-ii. i5 through-five,quarter-revolutions..sou that thethegknohlfigiscontinuous y ro a ed nether indicator pointe. registers; .in the positign 0,? words, one complete turn of;k no]o;iezcauseseone This will automatically'add 125; kiI QCYCIeSQtOLtHBJ completeeturn ofdial. llaaandaoneatenthtofat indicated setting; of the; dial l7, tandswillauto-fl completeiturn of "dial-J8 Whendial l8 haszmade matically adjust the transmitter l3.ito;the;newv one complete turnunderscontrolrof:knob":l6; dial:

frequency. If ordinarycounterzmechaxiismsweree I 9.rotates one-tenth ofua iturnjntermittentlyun p y pl y n a..single:=kn0h suohas the dercontrolof shaft BB-zandzsuitahleGenevaand1 knob 15, it would be necessary;to;turn the diall'l: stepe-downgear ratios. Dialrlgsthenxdrives dials a very great number, of,=timesein;order:.to arriveat. Hand. 21 .in:.a,tstandardicounting;drum.arrange-- the final setting Duringthis adiustmentcthe; iziementv However; aspOintedmut-a-bDVe; this man-- .7 transmitter would be inoperative,and;;va1uab1e.= n rt fk p n f h di l w n m transmission time; would her-10st; great amount of time-if the; transmitter :i 3 isto be Referring to Fig, 3, thereeise-shown in1isometrim successively un d fl e y W y d fi rent fre perspective themechanicallconnections;between quencies. For th L e mfi d the two knobs l5; l6,--and therespectivedial: eu toeeontrol the setting'of the seotions..l1b andfill;-

wheels. The;parts; 0f Fjg, Biwhich correspond, andthe fine orinterpolation:setting-rof thediale functionally to those-of FigeZ; beanthe samezdes "11:41amibewcontrolledibyi-lmeblisii ignation numerals The knobvlfi-ais'riastenedto here vis providedacdirectrindicationof the fre the shaft 43 which controlsthesettinghf theifine; que cy of the transmitter 13$ and e wo on selection circuit 12;. Likewiseetheknohefi isiasa tr0l1'ingknobs=;l5:andl6aare mechanically l e tened to the shaft .44. for; controlling!thee ooarsea during t a se Set ng Of dial I! and durin frequency selection; circuit. ll. Alsosiastenedito h erpola nis tt i the shaft portion-leis ar-zbeyel gear 45.1: which- While onaparticular embodiment has-been (fie-=- meshes with a correspondingwbevel gear 46 at scribed; it:willbe-understoodthatxzariousnhangee tached to.shaft.;22,, Shaita22 carriestthe disc. 4.1 j andi modifications .may bel made therein without and the laterally;extendingrdrivingupin- 48 which i departing from 'thespirit and scope of the incooperates with the slotted;driven.disc1&9; Disc vention.

i9 is fastened to shaft 50;whichcarriesotheeinter- Whatiscclaimed is:

mittent locking gear l whichlishimenga flmenti 1'. The combination of a '%vicewhich-is-arwith the correspondingenotched disc :52 rfastenedii ranged to b eadjusted-teeny desired-setting by to shaft 22. Thus aiterxeach:fiveurevolutions aof coarsetstepsand by fine steps and including rotatshaft fil the shaft 251isladyanced;one-revolution; able oontrol shaftsrespectively for the coarse- The shaft 25 also drives.thedntermitt nt spurand finesteps;and-*meanstoeount and indicatei ear arran em n =c0 prising theespur gears direetly the hem-beret turns-required-ior each and the Corresponding intermittent 0b shaft to cause-said deviceto' assume-its desired ing earsBZc, 32d. Gear. 32bi=isjfastenechtoshaft Setting; the a5t;menfioned; means inc1uding a 3| and the gearing is;such.that'there:is:aestep-= calibratednumerieal dial section-forthe'coarsedown gear ratio ofifiverto one between shaits .25.5 setting, a second oalihrated numerical dial iseca and 3|. Shaft 22,.- also carriesatspur: gears-2201i. tion for the'fine-setting, meanstotset the-coarse which meshes withx an idlerrgean 22b, .whicli in." dial sect-ionindependently of the fi'ne dial'section, and means to set the fine dial section to modify the setting of the coarse dial section with a desired number of fractional coarse steps.

2. The combination of a device which is arranged to be adjusted to any desired setting by coarse steps and by incremented fine steps and including respective rotatable control shafts for the coarse and fine steps, and means operated by said shafts to count and directly indicate the number of turns required for each shaft to cause said device to arrive at said desired setting, the last-mentioned means including a series of rotatable numerical dials one group of said dials indicating a number representing one of said coarse settings, another of said dials indicating a number representing a fractional part of said one of said coarse settings, means to set said group of dials independently of said other dial, and means to set said other dial to modify the setting of said group of dials in accordance with the required incremental fine steps.

3. The combination of a device which is arranged to be adjusted to any desired numerical setting by coarse steps and by incremental fine steps and including respective rotatable control shafts for the coarse and fine steps, a mechanical counting arrangement controlled by said shafts for directly indicating a plural digit number representing said desired setting, said counter comprising at least one rotatable numerical dial which indicates the coarse settings, and another rotatable numerical dial which indicates fractional parts of said coarse settings, means to set said coarse setting dial in steps independently of said other dial, and means to set said other dial so that it is cumulative with respect to the setting of the coarse dial.

4. The combination of a device which is arranged to be adjusted to any desired numerical setting by coarse steps and by incremental fine steps and including respective rotatable control shafts for the coarse and fine steps, a mechanical counting arrangement controlled by said shafts for directly indicating a plural digit number representing said desired setting, said counting ar rangement comp-rising a plurality of numerical dials to indicate successive coarse steps, another numerical dial to indicate the incremental steps, said plurality of numerical dials being coupled directly to each other for cumulative indication, means to set said incremental control dial throughout one revolution independently of. said plurality of dials, and means to set said plurality of dials throughout any desired number of revolutions independently of said incremental control dial.

5. The combination according to claim 4 in which means are provided for cumulatively modifying the setting of said plurality of dials when said incremental control dial is rotated through more than one complete revolution.

6. A direct frequenc indication arrangement for a frequency selecting system of the type which employs a coarse step-by-step frequency selector and an incremental or fine step-by-step frequency selector, comprising a, frequency indicator of the numerical dial counting type, said indicator having first and second dial sections, the first section indicating the coarse steps and the second section indicating the fine steps, means to set said first section under control of the step-by-step setting of said coarse frequency selector and independently of the setting of said fine frequency selector, and means to set said second section under control of the step-by- 3. step setting of said fine frequency selector to produce a final numerical indication of the frequency of desired setting of said system.

7. A direct frequency indicating arrangement according to claim 6 in which the last-mentioned means includes an adjusting knob which is connected to said second section to operate it in unison therewith, said knob being connected through step-down gearing to one of th dials of the said first section to operate it in step-by-step fixed ratio with respect to said second section.

8. A direct frequency indicating arrangement according to claim 6 in which the last-mentioned means includes an adjusting knob which is connected to said second section to be operated in unison therewith, said knob being connected through an intermittent step-down gearing arrangement to one of the dials of the said first section to operate it in a step-by-step fixed ratio with respect to said second section.

9. A direct frequency indicating arrangement according to claim 6 in which the last-mentioned means includes a common adjusting knob for the fine frequency selector and for said second dial section, said knob being connected to said second dial section to be operated in unison therewith, said knob also being connected serially through an intermittent gear movement and a step-down gearing arrangement and a differential gear to one of the dials of said first section to operate it in step-by-step fixed ratio with respect to said second section.

10. A direct frequency indicating arrangement for a frequency selecting system of the type which employs a coarse step-by-step frequency selector and an incremental or fin step-by-step frequency selector, comprising a frequency indicator of the numerical dial counting type, said indicator having first and second dial sections with the first section having at least two digit dials for indicating the coarse steps, and the said second section having a dial for indicating the fine steps, the dials of the first section arranged to be set in accordance with the step-by-step setting of said coarse frequency selector and independently of the setting of the fine frequenc selector, said second section arranged to be set in accordance with the step-by-step setting of said fine frequency selector to produce a final numerical indication of the frequency of the desired setting of said system, a first adjusting knob for controlling said first dial section independently of said second section, a second adjusting knob for controlling the said Second dial section, means connecting said second knob through a first differential gearing arrangement to one of the dials of the first section to operate it in fixed ratio with respect to th second dial section, and means connecting said second knob through a second differential gearing to another dial in said first section to operate it in fixed step-by-step ratio with respect to said one of said dials of the first section.

11. A direct reading frequency indicating arrangement according to claim 10 in which said, first knob is also connected to said one of said dials of the first section through said first differential gearing arrangement so that the setting of said one of the dials of the first section can be effected by said first knob independently of said 'second knob.

for the second and third sections, a gearing arrangement between the first knob and the first section for adjusting the first section independently of the second section, means connecting the second knob to the second section for setting it in unison therewith, and other means connecting said second knob to at least one dial of the first section to rotate it in fixed step-by-step ratio with respect to the dial of the second section.

13. A numerical counting dial system accord ing to claim. 12 in which the last-mentioned means includes a differential which is also connected to the first knob to enable said one dial of the first section to be set under control of the first knob independently of the second knob.

14. A numerical indicating dial system of the type described, comprising three numerical dials, a first adjusting member for setting the first and second dials independently of the setting of the third dial, a second adjusting member for setting the third dial throughout one revolution independently of the setting of the first and second dials, and means connecting said second adjustin member to said second and third dials to modify their setting in accordance with the total number of revolutions of said third dial.

15. A numerical indicating dial system of the type described, comprising three numerical dials, a first adjusting member for setting the first and second dials independently of the setting of the third dial, a second adjusting member for setting the third dial, a first difierential gear which is connected between the first dial and both of said adjusting means, a second difierential gear which is connected between the second dial and both of said adjusting means, said differential gears cooperating With both of said adjusting means to enable the first and second dials to be set in fixed ratio by said first adjusting means independently of said second adjusting means, and the setting of said third dial being efiected by said second adjustin means independently of said first adjusting means.

16. A numerical indicating dial system of the type described, comprising first, second and third numerical dials, the second and third dials ar ranged to indicate coarse steps and the first dial arranged to indicate fractional parts of said coarse steps, a first adjusting knob, a second adjusting knob, a first differential gear controlled by said first knob for controlling the setting of the second dial, said first differential gear also being under control of said second knob to independently control the setting of said second gear without disturbing the first knob, a second differential gear controlled by the first knob for controlling the setting of the third dial, said second difierential also being controllable by said second knob to control the settin of said third gear independently of said first knob.

17. A numerical indicating dial arrangement of the type described, comprising first, second and third digit dials, a first adjusting knob, a second adjusting knob, means to set said first dial in unison with the setting of said first knob, an intermittent gear movement controlled by said first knob, a difierential gear controlled by said intermittent gear movement, said differential being connected to the second dial whereby said second dial is operated by said first knob in steps of one to ten ratio with respect to the operation of the first dial, an intermittent gear also controlled by said intermittent gear movement, a. second difierential gear controlled by said intermittent gear, another intermittent gear connected between said second differential and said third dial to cause said third dial to be set in steps by said first knob at the ratio of one to one hundred with respect to the setting of the first dial, and means to control said differentials independently by said second knob to set the second and third dials under control of said second knob independently of the setting of the first dial by said first knob.

ALBERT E. BACHMANN.

No references cited. 

